Matrix assisted laser desorption time-of-flight (MALDI-TOF) mass spectrometers are highly robust and capable instruments for bio-molecular analysis. MALDI-TOF mass spectrometry has been applied for identification of bacterial and viral pathogens, clinical pathology, tissue imaging, biochemistry, health research, etc. Routine performance specifications for reflector MALDI-TOF instruments often exceed 15,000 for resolution and <5 ppm for accuracy with internal calibration. Higher level instruments may exceed these specifications. This performance is sufficient for most biological applications including protein identification by peptide mass fingerprinting, a technique that is highly dependent on high accuracy mass measurements of component peptides. For this reason, after resolutions exceeding 10,000 are attained, instrument accuracy is as important, if not more important, than resolution for most peptide and protein analyses.